[wasm-simd][x64] Check for register when emitting shuffles

Some shuffles take have either register or memory operand for second
input, but the codegen incorrectly assumes that it is always a register.

Bug: v8:10824
Change-Id: Ia2df233dad4ed451e52e57e35cce5c80db0905db
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2373586
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69562}

src/codegen/x64/assembler-x64.h

@@ -1646,6 +1646,10 @@ class V8_EXPORT_PRIVATE Assembler : public AssemblerBase {
     vinstr(0x0F, dst, src1, src2, k66, k0F3A, kWIG);
     emit(imm8);
   }
+  void vpalignr(XMMRegister dst, XMMRegister src1, Operand src2, uint8_t imm8) {
+    vinstr(0x0F, dst, src1, src2, k66, k0F3A, kWIG);
+    emit(imm8);
+  }
 
   void vps(byte op, XMMRegister dst, XMMRegister src1, XMMRegister src2);
   void vps(byte op, XMMRegister dst, XMMRegister src1, Operand src2);

src/compiler/backend/x64/code-generator-x64.cc

@@ -667,10 +667,14 @@ void EmitWordLoadPoisoningIfNeeded(CodeGenerator* codegen,
     ASSEMBLE_SIMD_INSTR(opcode, dst, input_index);       \
   } while (false)
 
-#define ASSEMBLE_SIMD_IMM_SHUFFLE(opcode, imm)                            \
-  do {                                                                    \
-    DCHECK_EQ(i.OutputSimd128Register(), i.InputSimd128Register(0));      \
-    __ opcode(i.OutputSimd128Register(), i.InputSimd128Register(1), imm); \
+#define ASSEMBLE_SIMD_IMM_SHUFFLE(opcode, imm)                              \
+  do {                                                                      \
+    DCHECK_EQ(i.OutputSimd128Register(), i.InputSimd128Register(0));        \
+    if (instr->InputAt(1)->IsSimd128Register()) {                           \
+      __ opcode(i.OutputSimd128Register(), i.InputSimd128Register(1), imm); \
+    } else {                                                                \
+      __ opcode(i.OutputSimd128Register(), i.InputOperand(1), imm);         \
+    }                                                                       \
   } while (false)
 
 #define ASSEMBLE_SIMD_ALL_TRUE(opcode)          \

test/cctest/test-disasm-x64.cc

@@ -817,6 +817,7 @@ TEST(DisasmX64) {
       __ vpblendw(xmm1, xmm2, xmm3, 23);
       __ vpblendw(xmm1, xmm2, Operand(rbx, rcx, times_4, 10000), 23);
       __ vpalignr(xmm1, xmm2, xmm3, 4);
+      __ vpalignr(xmm1, xmm2, Operand(rbx, rcx, times_4, 10000), 4);
 
       __ vblendvpd(xmm1, xmm2, xmm3, xmm4);